Coil springs for cable support

Abstract

Helically wound coil springs are wrapped around and attached at regular intervals to a cable, which is positioned within tubing. The support springs are attached to the cable to provide support to the cable. The upper section of each support spring is affixed to the cable. A remainder of each spring is formed in a long open helix facing downward when the tubing is installed in a well. The open helix portion of the spring is larger than the inside diameter of the coiled tubing. During placement into the coiled tubing, the springs elongate and decrease in diameter. When the coiled tubing is installed vertically within a well, the springs compress due to the weight of the cable and engage the inside surface of the coiled tubing with a substantial portion of their length, thereby supporting the cable.

What is claimed is:  
     
       1. An apparatus for supporting weight of a cable within tubing in a well, comprising: 
       a length of tubing;  
       an electrical cable within the tubing; and  
       at least one spring having a connecting section affixed to the cable and a helical section which engages an inside surface of said tubing and provides axial support to said cable to restrict downward movement of said cable in said tubing during use.  
     
     
       2. An apparatus according to  claim 1  wherein said connecting section is a clamp for engagement with said cable. 
     
     
       3. An apparatus according to  claim 1  wherein an outer surface of said spring is knurled for engagement with said inside surface of said tubing. 
     
     
       4. An apparatus according to  claim 1  wherein said helical section of said spring has a free end and frictionally engages said inside surface of said tubing. 
     
     
       5. An apparatus according to  claim 1  wherein said helical section of said spring has a free end that is sharpened and frictionally engages said inside surface of said tubing. 
     
     
       6. An apparatus according to  claim 1  wherein said helical section of said spring has a free end that is hardened. 
     
     
       7. An apparatus according to  claim 1  wherein said at least one spring comprises a plurality of springs. 
     
     
       8. An apparatus according to  claim 1  wherein said helical section of said spring has a maximum outer diameter that frictionally engages said inside surface of said tubing for providing axial support to said cable. 
     
     
       9. An apparatus according to  claim 1  wherein said spring has a square cross-section. 
     
     
       10. An electrical line for supporting weight of a cable within tubing in a well, comprising: 
       a string of tubing;  
       an electrical cable having at least one insulated conductor and a metal armor strip that is wrapped around said electrical cable, the electrical cable being inserted within the tubing; and  
       at least one spring having a connecting section affixed to said cable, said spring further comprising a helical section having a maximum outer diameter that frictionally engages an inside surface of said tubing for providing axial support to said cable to restrict downward movement of said cable in said tubing during use.  
     
     
       11. An electrical line according to  claim 10  wherein said connecting section is comprised of a clamp. 
     
     
       12. An electrical line according to  claim 10  wherein said outer diameter of said helical section is knurled. 
     
     
       13. An electrical line according to  claim 10  wherein a free end of said helical section of said spring is sharpened and frictionally engages said inside surface of said tubing. 
     
     
       14. An electrical line according to  claim 10  wherein a free end of said helical section of said spring is hardened. 
     
     
       15. An electrical line according to  claim 10  wherein a free end of said helical section of said spring is sharpened and hardened. 
     
     
       16. An electrical line according to  claim 11  wherein said spring has a square cross-section. 
     
     
       17. A method of supporting weight of an electrical cable within a length of tubing in a well comprising: 
       affixing a first end of a plurality of support springs onto a cable, each of said support springs having a second end which surrounds at least a portion of said cable;  
       pulling said cable and said support springs into a length of tubing that is sized so that an outer diameter of each of the springs frictionally engages an inner surface of the tubing length;  
       lowering said tubing into a well, the cable having a weight resulting in a locking action between said inside surface of said tubing length and said support springs; and supporting the weight of said electrical cable with said support springs.  
     
     
       18. A method of supporting a cable within a length of tubing according to  claim 17  wherein said support springs are stretched during pulling of said cable into said tubing length, resulting in an increase in length and reduction in diameter of said support springs. 
     
     
       19. A method of supporting a cable within a length of tubing according to  claim 17  wherein the weight of said cable applies a downward force on said support springs, resulting in a shortening of said support springs and an increase in an outside diameter of said support springs for forcing an engagement between outer diameters of said support springs and an inner diameter of said tubing length over a substantial length of each of said support springs. 
     
     
       20. A method of installing a cable within a length of tubing for use in a well comprising the steps of: 
       affixing a plurality of support springs to a power cable, wherein said support springs have an attached end and a free end;  
       installing said power cable in the length of tubing, wherein said attached end of said support springs enter said tubing before said free end of said support springs; and  
       engaging an inside surface of said tubing with said support springs, which results in a dragging force and elongation of said springs.  
     
     
       21. The method of installing according to  claim 20  wherein: 
       said power cable has helically wrapped metal armor configuration; and  
       said attached end of said support spring has a helical configuration for complementary engagement with said helically wrapped metal armor.